No Birghtness control on DELL Inspiron N4010

[Gfurst]

Hello folks, I've installed Ubuntu 13.04 on my machine, Dell Inspiron N4010, a couple of days ago, after setting most things i cannot get brightness control.
The bright function keys do work, the slider even shows on right upper corner, but it does not change. Even the System Settings >> Birghtness and Lock, i can move the slider but no change.
This is a known issue with Inspiron, lost of post around and there's even a work around it:

echo X | sudo tee /sys/class/backlight/intel_backllight/brightness

Where X is the bright value from 1 to 4500 something. This works but is not functional.

Now, what i would like help with, is how to set up a functional work around, maybe as a starting script might work, but i won't be able to easily change brightness.
The /sys/class/backlight folder has two items, the intel_backlight and the dell_backlight one. Is there a way to choose between the two? I would prefer Dell.
Another user reported a 0video driver instead of the intel, and it works, any way to install and use this one instead?

Or finally if nothing works, a startup script to set brightness a bit low( it always turn on too strong), or a script to bind to the brightness keys?
Thanks, any help or suggestion is welcome.

[Toz]

Can you post back the results of the following commands for more information to see if a workaround can be drafted up:
1. Your current kernel command line:

cat /proc/cmdline

2. Info on your video cards:

sudo lspci -vnn | grep -A12 VGA

3. Your backlight interfaces and current values:

for i in /sys/class/backlight/*; do echo $i; cat $i/brightness; cat $i/max_brightness; done

4. Acpi codes for your brightness function keys. First, open a terminal window and enter the following command:

acpi_listen

...the press once the function+brightness up combination and once the function+brightness down key combination. Then, post back what codes are dispalyed in the terminal window.

Hopefully we can try to replicate something like this for your laptop.

[Gfurst]

Hey Toz thanks for the thoughtful reply, in order:

1. My current system command line

BOOT_IMAGE=/boot/vmlinuz-3.8.0-25-generic root=UUID=665bde14-86b6-4d47-a4c6-59abb57daee3 ro quiet splash vt.handoff=7

2. Video info

00:02.0 VGA compatible controller [0300]: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 18) (prog-if 00 [VGA controller])
    Subsystem: Dell Device [1028:0456]
    Flags: bus master, fast devsel, latency 0, IRQ 42
    Memory at f0000000 (64-bit, non-prefetchable) [size=4M]
    Memory at d0000000 (64-bit, prefetchable) [size=256M]
    I/O ports at 1800 [size=8]
    Expansion ROM at <unassigned> [disabled]
    Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
    Capabilities: [d0] Power Management version 2
    Capabilities: [a4] PCI Advanced Features
    Kernel driver in use: i915

00:16.0 Communication controller [0780]: Intel Corporation 5 Series/3400 Series Chipset HECI Controller [8086:3b64] (rev 06)

3.Brightness stuff

/sys/class/backlight/dell_backlight
15
15
/sys/class/backlight/intel_backlight
4882
4882

4.Brightness keys

video DD02 00000087 00000000
video DD02 00000086 00000000

So as i thought, two different backlight drivers, brightness keys do work though, Unity's pop up for brightness shows up as expected but no changes occur.
Saw the link, its certainly a type of solution, i went looking for something filed as a bug that would fit, and came up with: http://ubuntuforums.org/showthread.php?t=2148814
LoL, gonna try the acpi_backlight=vendor, as i know the acpi_osi=!windows_2012 did not work for me.

[Toz]

Okay. I would try the following kernel parameters (one set at a time, remember to run "sudo update-grub" and reboot afterwards):

acpi_osi=

acpi_osi=Linux acpi_backlight=vendor

Note: the acpi_osi=\"!Windows 2012\" is a tricky one. The 2 important lines in your /etc/default/grub file should look like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi=\"!Windows 2012\""

[Gfurst]

Hey the following didn't yield any results

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Just to be clear, the first two parameters are supposed to go "LINUX_DEFAULT=" or the "LINUX=" line in grub's config?
Or it just doesn't make much of difference?

[Toz]

It doesn't really matter which line, but its cleaner if you leave the defaults in the GRUB_CMDLINE_LINUX_DEFAULT line and put any additional parameters that you want to add in GRUB_CMDLINE_LINUX. You can check to see if they are applied by seeing if they show up when running the following command:

cat /proc/cmdline

I have a feeling these won't work for you, but give it a try anyways. You may have to fill in a bug report to get it properly dealt with. We can always create a workaround to get you access to the brightness controls.

EDIT: I think this might be the relevant bug report: https://bugs.launchpad.net/ubuntu/+s...n/+bug/1105604

[Gfurst]

Hey Toz, thanks, i was searching for that bug report without success.
I'll try the grub options tomorrow, sorry for taking too long, but took some time installing Win7 straight out of the recovery partition, then the bastard wiped out my system's partition, luckily it was easy to reinstall.
Now both working

I too think those will not work, let's see tomorrow. See ya

[Gfurst]

Hey back here, tested all of the boot parameters, none worked:

BOOT_IMAGE=/boot/vmlinuz-3.8.0-25-generic root=UUID=a70a4762-30a7-429a-8250-08ee55791a8d ro "acpi_osi=!Windows 2012" quiet splash vt.handoff=7

The grub part was exactly as you told me, I wonder if the comas could make a difference.

Anyway, one interesting thing, after i reboot from windows, where i can change brightness, i carries over to Ubuntu, even though i can't change it starts dimmed.
Another interesting thing is that changing brightness via command line

echo X > /sys/class/backlight/intel_backlight/brightness

Will throw permission denied, maybe this could be a cause of user not being able to change.
Another thing i thought about is that i should be using the dell_backlight instead of intel_backlight.
Another user reported working same configuration but with a /backlight/video0, generic perhaps?

I will keep a look at the launchpad bug and also back it up, have to create account first.

[Toz]

Another interesting thing is that changing brightness via command line

echo X > /sys/class/backlight/intel_backlight/brightness

Will throw permission denied, maybe this could be a cause of user not being able to change.

This is because as a user you don't have access to that location. You need root privledges. Try instead:

echo X | sudo tee /sys/class/backlight/intel_backlight/brightness

I will keep a look at the launchpad bug and also back it up, have to create account first.

Your best bet may be to follow that bug report.

As for a workaround, which one of your backlight interfaces responds with brightness changes:

echo 7 | sudo tee /sys/class/backlight/dell_backlight/brightness
echo 15 | sudo tee /sys/class/backlight/dell_backlight/brightness

...or

echo 2441 | sudo tee /sys/class/backlight/intel_backlight/brightness
echo 4882 | sudo tee /sys/class/backlight/intel_backlight/brightness

[Gfurst]

This is because as a user you don't have access to that location. You need root privledges.

What i meant was that the whole problem's source, could be the user( the acpi keys group or whatever) that is supposed to control that brightness does not have access.
Anyway, I'll let that part people who actually know about it.

For the work around, the drive used is intel_backlight, the sudo tee code( found on another post) i did use it when it was too bright.
In fact just a startup script to set brightness to around 20% might be good enough.
I've guess a scripted solution for the keys could be hard, the permission thing would get in the way.

Thanks Toz